Exchange rate manipulation refers to a country’s large-scale unilateral intervention in the exchange rate for its own profit, which has always been an important excuse for the United States to launch a trade war. Whenever there is a large trade deficit in the United States, the United States always accuses other countries of gaining trade surplus advantage through exchange rate manipulation, forcing other countries to appreciate their currencies and improving the trade deficit with a weak dollar policy.　　Elasticity analysis is an important method to study the relationship between exchange rate and trade. Marshall-Lerner condition （M-L condition） is an important criterion. According to M-L condition, if the absolute value of price elasticity of import and export demand is greater than 1, then the devaluation of the local currency can improve the trade deficit （Lerner, 1944）. This study shows that the M-L condition of all industries in the United States is not satisfied, and the weak dollar policy can not improve the trade deficit of the United States.　　There is an obvious phenomenon of " potential anti-comparative advantage” in American foreign trade. Ju Jiandong and Ma Hong （2012） pointed out the phenomenon of anti-comparative advantage in Sino-US trade, and called this abnormal phenomenon " the riddle of anti-comparative advantage”. The results of this study show that the " riddle of anti-comparative advantage” exists not only in the US-China trade, but also in the US trade with Germany, Japan and Mexico. Because of its wide scope, special nature and hidden implementation, this paper calls it the " potential anti-comparative advantage phenomenon”. " Potential anti-comparative advantage” is the result of the overlapping of trade inertia, trade structure and trade policy. It is also an important reason for the current account deficit of the United States.　　This paper uses the import and export trade data of HS quartile industry between the United States and its five major source countries of trade deficit after the financial crisis to analyze the causes of the formation of the trade deficit in the United States. The analysis results not only confirm the existence of " potential anti-comparative advantage phenomenon”, but also point out that compared with exchange rate factors, economic factors, structural factors and institutional factors are the most important factors affecting the trade deficit in the United States. This is not only an effective supplement to the existing literature, but also an effective refutation to the accusation of US exchange rate manipulation. This enlightens that if the United States firmly grasps the exchange rate problem of other countries, it cannot solve the problem. Only by changing the existing export technology restriction policy and increasing exports of comparative advantage products to other countries, especially China, can the trade deficit situation be reversed. This study is of great significance for correctly recognizing the relationship between exchange rate and trade, and strongly refuting the accusation of exchange rate manipulation in the United States.